Why remote Antarctica is so important in a warming world


Chris Fogwill, Keele University; Chris Turney, UNSW, and Zoe Robinson, Keele University

Ever since the ancient Greeks speculated a continent must exist in the south polar regions to balance those in the north, Antarctica has been popularly described as remote and extreme. Over the past two centuries, these factors have combined to create, in the human psyche, an almost mythical land – an idea reinforced by tales of heroism and adventure from the Edwardian golden age of “heroic exploration” and pioneers such as Robert Falcon Scott, Roald Amundsen and Ernest Shackleton.

Recent research, however, is casting new light on the importance of the southernmost continent, overturning centuries of misunderstanding and highlighting the role of Antarctica in how our planet works and the role it may play in a future, warmer world.

Heroic exploration, 1913.
wiki

What was once thought to be a largely unchanging mass of snow and ice is anything but. Antarctica holds a staggering amount of water. The three ice sheets that cover the continent contain around 70% of our planet’s fresh water, all of which we now know to be vulnerable to warming air and oceans. If all the ice sheets were to melt, Antarctica would raise global sea levels by at least 56m.

Where, when, and how quickly they might melt is a major focus of research. No one is suggesting all the ice sheets will melt over the next century but, given their size, even small losses could have global repercussions. Possible scenarios are deeply concerning: in addition to rising sea levels, meltwater would slow down the world’s ocean circulation, while shifting wind belts may affect the climate in the southern hemisphere.

In 2014, NASA reported that several major Antarctic ice streams, which hold enough water to trigger the equivalent of a one-and-a-half metre sea level rise, are now irreversibly in retreat. With more than 150m people exposed to the threat of sea level rise and sea levels now rising at a faster rate globally than any time in the past 3,000 years, these are sobering statistics for island nations and coastal cities worldwide.

An immediate and acute threat

Recent storm surges following hurricanes have demonstrated that rising sea levels are a future threat for densely populated regions such as Florida and New York. Meanwhile the threat for low-lying islands in areas such as the Pacific is immediate and acute.

Much of the continent’s ice is slowly sliding towards the sea.
R Bindschadler / wiki

Multiple factors mean that the vulnerability to global sea level rise is geographically variable and unequal, while there are also regional differences in the extremity of sea level rise itself. At present, the consensus of the IPPC 2013 report suggests a rise of between 40 and 80cm over the next century, with Antarctica only contributing around 5cm of this. Recent projections, however, suggest that Antarctic contributions may be up to ten times higher.

Studies also suggest that in a world 1.5-2°C warmer than today we will be locked into millennia of irreversible sea level rise, due to the slow response time of the Antarctic ice sheets to atmospheric and ocean warming.

We may already be living in such a world. Recent evidence shows global temperatures are close to 1.5°C warmer than pre-industrial times and, after the COP23 meeting in Bonn in November, it is apparent that keeping temperature rise within 2°C is unlikely.

So we now need to reconsider future sea level projections given the potential global impact from Antarctica. Given that 93% of the heat from anthropogenic global warming has gone into the ocean, and these warming ocean waters are now meeting the floating margins of the Antarctic ice sheet, the potential for rapid ice sheet melt in a 2°C world is high.

In polar regions, surface temperatures are projected to rise twice as fast as the global average, due to a phenomenon known as polar amplification. However, there is still hope to avoid this sword of Damocles, as studies suggest that a major reduction in greenhouse gases over the next decade would mean that irreversible sea level rise could be avoided. It is therefore crucial to reduce CO₂ levels now for the benefit of future generations, or adapt to a world in which more of our shorelines are significantly redrawn.

This is both a scientific and societal issue. We have choices: technological innovations are providing new ways to reduce CO₂ emissions, and offer the reality of a low-carbon future. This may help minimise sea level rise from Antarctica and make mitigation a viable possibility.

Given what rising sea levels could mean for human societies across the world, we must maintain our longstanding view of Antarctica as the most remote and isolated continent.The Conversation

Chris Fogwill, Professor of Glaciology and Palaeoclimatology, Keele University; Chris Turney, Professor of Earth Sciences and Climate Change, UNSW, and Zoe Robinson, Reader in Physical Geography and Sustainability/Director of Education for Sustainability, Keele University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

We must strengthen, not weaken, environmental protections during drought – or face irreversible loss



File 20180924 129862 1fr9qma.jpg?ixlib=rb 1.1
The Flock Bronzewing is an inland species that is vulnerable to drought. Those vulnerabilities are heightened in an era of climate change and increased risks from feral predators.
Shutterstock

John Woinarski, Charles Darwin University; Chris Dickman, University of Sydney; Richard Kingsford, UNSW, and Sarah Legge, Australian National University

Australian rural communities face hardships during extended drought, and it is generally appropriate that governments then provide special support for affected landholders and communities.

However, some politicians and commentators have recently claimed that such circumstances should be addressed by circumventing environmental laws or management – by, for example, reallocating environmental water to grow fodder or opening up conservation reserves for livestock grazing.

But subverting or weakening existing protective conservation management practices and policies will exacerbate the impacts of drought on natural environments and biodiversity.




Read more:
Giving environmental water to drought-stricken farmers sounds straightforward, but it’s a bad idea


Drought-related decline in wildlife

Impacts of severe weather on some natural systems are obvious and well-recognised. For example, during periods of elevated sea temperature, coral bleaching may conspicuously signal extensive environmental degradation and biodiversity loss.

On land, however, the impacts of comparable extreme climatic events on natural systems may be less obvious, even if of comparable magnitude.

Nonetheless, the record is clear: drought leads to extensive and severe declines in many wildlife species.

Early observers in Australia reported the collapse of bird communities (“the bush fell silent”) and other wildlife across vast areas during the Federation Drought.

There were comparable responses during the Millennium Drought.

Unsurprisingly, wetland environments, and species dependent on them, may bear the brunt of impacts. That said, impacts are pervasive across all landscapes exposed to drought.

Drought contributed to the extinction of one of Australia’s most beautiful birds, the Paradise Parrot. For example, the pastoralist and zoologist Charles Barnard noted:

Previous to the terrible drought of 1902 it was not uncommon to see a pair of these birds when out mustering … but since that year not a single specimen has been seen … For three years… there had been no wet season, and very little grass grew, consequently there was little seed; then the worst year came on, in which no grass grew, so that the birds could not find a living, and … perished … they have not found their way back.

Drought contributed to the extinction of one of Australia’s most beautiful birds, the Paradise Parrot.
Wikimedia, CC BY

After the long droughts break, native plant and animal species may take many years to recover, and some never recover or return to their former range.

Threatened plant and animal species – with an already tenuous toe-hold on existence – are often the most affected.

Days of extremely hot temperatures also exceed the thermoregulatory tolerance of some species. That means mass mortality for some animals; and large numbers of even hardy native trees may be killed by heat and lack of rain across extensive areas.

Furthermore, water sources can disappear from much of the landscape. Organisms dependent on floods are now more vulnerable, given that overallocation of water from rivers has increased drying of wetlands.

Drought is not new in Australia, but the stresses are greater now

Of course, drought has long been a recurrent characteristic of Australia. Indeed, many Australian plants and animals are among the most drought-adapted and resilient in the world. But drought impacts on wildlife are now likely to be of unprecedented severity and duration, for several reasons:

  1. with global climate change, droughts will be more severe and frequent. There will be less opportunity for wildlife to recover in the reduced interval between drought periods

  2. feral cats and introduced foxes now occur across most of Australia. In drought periods, these hunt more effectively because drought reduces the ground-layer vegetation that many native prey species rely upon for shelter. Cats and foxes also congregate and hunt more efficiently as wildlife cluster around the few water sources that are left

  3. prior to European settlement, the reduction in vegetation during drought would have been accompanied by natural feedback loops, notably reduction in the density of native herbivores. Now, livestock are often maintained in drought-affected areas, with supplementary food provided, but they also graze on what little native vegetation remains. Now, wildlife must compete with feral goats, camels and rabbits for the last vestiges of vegetation

  4. clearing of native vegetation across much of the eastern rangelands means it will now be much harder for species lost from some areas during drought to recolonise their former haunts after drought. The habitat connectivity has been lost

  5. many wildlife species could previously endure drought by maintaining a residue of their population in small refuge areas, where nutrients or moisture persisted in an otherwise hostile landscape. Now, livestock, feral herbivores and predators also congregate at these areas, making them less effective as native wildlife refuges

  6. in at least woodland and forest habitats, droughts may interact with other factors. Notably, drought increases the likelihood of high intensity and extensive bushfires that can cause long-lasting damage to wildlife and environments.




Read more:
Australia burns while politicians fiddle with the leadership


Our intention here is not to downplay the needs or plight of rural communities affected by drought.

Rather, we seek to bring attention to the other life struggling in that landscape. Australia should bolster, not diminish, conservation efforts during drought times. If we don’t, we will suffer irretrievable losses to our nature.The Conversation

John Woinarski, Professor (conservation biology), Charles Darwin University; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Richard Kingsford, Professor, School of Biological, Earth and Environmental Sciences, UNSW, and Sarah Legge, Associate Professor, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.